Electrodynamic relay



SR RH'EKHQUE Mam mum K. E. HASTINGS Nov. 6, 1962 ELECTRODYNAMIC RELAY 5 Sheets-Sheet 1 Filed May 25, 1960 FIG.

FIG. 4

lNl/ENTOR llllllllllllllllllll I llllllllllllllllllll l KENNETH E H TIN BYM ' ATTORNEY Nov. 6, 1962 HASTINGS 3,062,935

' ELECTRODYNAMIC RELAY Filed May 25. 1960 5 sheets-sheet 2 Nov. 6, 1962 K. E. HASTIN S 3,062,935

ELECTRODYNAMIC RELAY Filed May 25. 1960 3 Sheets-Sheet 3 itd States Patet 3,062,935 ELECTRODYNAMIC RELAY Kenneth E. Hastings, Rochester, Minn., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed May 23, 1960, Ser. No. 31,153 7 Claims. (Cl. 20087) This invention relates to an electrodynamic relay and, more particularly, to an electrodynamic relay adapted to operate at relatively low voltages and high speeds.

The electrodynamic relay in the present invention operates on the well-known principle that a conductor located in a magnetic field will tend to move out of the magnetic field in a direction perpendicular to the magnetic lines of force when a current is passed through the conductor. The force upon the conductor is according to the equation F=Bil cos wherein:

B=air-gap magnetic flux density,

i=current flowing in the conductor,

l=the length of conductor in the magnetic field, 0=relative angle between conductor and magnetic field.

In the present invention, the conductors are in the form of a flat coil adherent to both sides of a thin dielectric sheet. The coil upon one side of the dielectric sheet is connected in series with the coil disposed upon the other side. The dielectric sheet carrying the coils is disposed between a pair of permanent magnets oriented relative to each other so that the magnetic field is perpendicular to the conductors upon the dielectric sheet. The coils are in the form of a rectangular loop so that current, when applied to the coil, flows in one direction through the conductors of the lower half of the coils and in an opposite direction through the conductors of the upper half of the coils. However, the conductors of the lower half of the coils are associated 'with a first pair of opposite magnetic poles and the conductors of the upper half of the coils are associated with a second pair of opposite magnetic poles oppositely arranged from the arrangement of said first pair of opposite magnetic poles. The dielectric sheet is free to move relative to the magnets. When current is passed through the conductors forming the coils, the dielectric sheet is moved relative to the magnetic field. Because of the particular arrangement for the coils and pairs of magnetic poles, the forces upon the conductors of the lower half of the coils are additive to the forces upon the conductors of the upper half of the coils. As the dielectric sheet moves in response to the forces upon the conductors forming the coils, it acts upon electrical contacts.

In conventional electromagnetic relays, the force upon the armature or member for transferring the electrical contacts is'a function of the distance that the armature is from the core of the magnet. Hence, the force upon the armature is not uniform. Generally, the starting force is small and then the force increases as the armature approaches the core of the magnet. It is apparent that this type of relay is a slower operating relay than the one of the present invention where the forces developed, as current is passed through the coils, are uniform. Hence, once the current builds up, a peak force will be acting at all times to displace the dielectric sheet for transferring the contacts of the relay.

Another desirable feature is that the structure of the instant relay lends itself to automated production and assembly techniques. Therefore, the resultant relay is relatively inexpensive. The conductors forming the coils upon the dielectric sheet are produceable by well-known techniques for manufacturing printed circuitry. While the magnets may be any suitable permanent magnets or 3,062,935 Patented Nov. 6, 1962 ice ' electromagnets, it is possible to mold both the housing and the magnets out of ceramic material and then polarize the ceramic material at the desired locations to form the magnetic circuit. Not only does this arrangement lend itself to automated techniques, but ceramic material would permit operation at higher temperatures.

The coils of the relay have a low resistance to current flow and, therefore, the relay may operate at relatively low voltages. Relays capable of operating at low voltage are desirable because they are more compatible with solidstate electronic circuitry, such as transistor circuitry.

Accordingly, a prime object of the invention is to provide an improved electrodynamic relay.

Another object of the invention is to provide an electrodynamic relay which is capable of operating at low voltages.

Still another object of the invention is to provide an electrodynamic relay which is adapted to operate at relatively high speeds.

An additional object of the invention is to provide an electrodynamic relay which operates with a uniform maximum force.

Yet another object of the invention is to provide an electrodynamic relay which is capable of operating at relatively high temperatures.

A very important object of the invention is to provide an electrodynamic relay which is relatively inexpensive to manufacture.

The foregoing and other objects, features and advantages of the invention 'will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is a front elevational view of the relay;

FIG. 2 is a side elevational view of the relay;

FIG. 3 is a schematic view showing the magnetic members and the magnetic field;

FIG. 4 is a partial view in side elevation showing an alternate contact structure;

FIG. 5 is a schematic showing of the coils upon the dielectric sheet;

FIG. 6 is partial view in front elevation showing an alternate form for connecting the coils to supply term'inals;

FIG. 7 is a sectional view taken along the line 7-7 in FIG. 1;

FIG. 8 is perspective view schematically showing a sliding type of contact structure;

FIG. 9 is a perspective view schematically showing another sliding type of contact structure;

FIG. 10 is a perspective view schematically showing an arrangement where the dielectric sheet carries an adherent conductor adapted to establish an electrical connection with contact elements;

FIG. 11 is a partial view in side elevation showing another type of contact structure; and,

FIG. 12 is a perspective view schematically showing a sliding contact arrangement for connecting the coils to supply terminals.

With reference to the drawings and particularly to FIGS. 1 and 2, the invention is illustrated by way of example as a relay 10. The relay 10 includes permanent magnetic members 11 and 12 fixed opposite each other with opposite poles facing each other. The magnetic members 11 and 12 are fixed relative to a rectangular frame 13 either by suitable fastening means or by the mutual attractive force of the magnetic members 11 and 12. The magnetic members 11 and 12 are rectangular in shape and are provided with longitudinal grooves 14 and 15, respectively, which separate the poles of the magnetic members. The dimensions of the grooves 14 and are critical and will be discussed subsequently.

The frame 13, as seen in FIG. 7, includes a rib member 16 which functions to space the magnetic members 11 and 12 from each other. In this example, the rib member 16 is approximately 40 mils thick. Hence, the magnetic members 11 and 12 are spaced 40 mils apart. The spacing between the magnetic members should be kept to a minimum so that the reluctance between magnetic members is low. To some degree, there is a practical limit because of limitations of known materials and techniques for producing thin conductors adherent to a thin dielectric sheet. It is expected that, as these techniques and materials improve, the spacing between magnetic members could be reduced. The depth and width of the longitudinal grooves 14 and 15 in the magnetic members 11 and 12, respectively, are related to the amount of spacing between the magnetic members 11 and 12. The width of the grooves 14 and 15 is approximately twice the amount of spacing between the magnetic members 11 and 12. The depth of the grooves 14 and 15 is critical in connection with the width of the grooves. In order to avoid a low reluctance magnetic path between poles of one of the magnetic members, the depth of the groove should approximately be equal to the width of the groove. With this arrangement, while there will be some fringing of magnetic flux between poles of the same magnetic member, a low reluctance magnetic path is provided between the op posite poles of the oppositely disposed magnetic members, as shown in FIG. 3. The strength of the magnetic field developed between the magnetic members 11 and 12 is, of course, dependent upon the reluctance of the magnetic path. The lower the reluctance, the stronger is the magnetic field. The stronger the magnetic field, the greater is the force developed upon conductors and 21 adherent to opposite sides of the dielectric sheet 25, FIG. 5.

The dielectric sheet is rectangular in shape and is approximately 32 mils thick. The thickness of the conductors 20 and 21 adherent to the dielectric sheet 25 is approximately 2 mils for the conductors on each side; hence, the composite structure is approximately 36 mils. The dielectric sheet 25 with the conductors 20 and 21 is freely contained on edge between the magnetic members 11 and 12 with approximate clearance of 2 mils on each side. The dielectric sheet rests on edge upon the bottom of the housing 13, as seen in FIGS. 1 and 2. In this example, FIG. 5, the conductors 20 and 21 are connected in series by a through connection, such as metallic rivet 22, and are formed upon the dielectric sheet 25 in coils 23 and 24 so that current will flow in the same direction in the conductors 20 and 21. Of course, current flows through the conductors 20 and 21 disposed within the upper portion of the dielectric sheet in one direction and in the opposite direction through the conductors 20 and 21 disposed within the lower portion of the dielectric sheet. By this arrangement, the energizing current passes between one pair of poles of magnetic members 11 and 12 in one direction and in the opposite direction between the other pair of poles. The forces upon the upper and lower conductors 20 and 21, therefore, act in the same direction to displace the dielectric sheet 25 away from the bottom of the housing or frame 13.

As shown in FIGS. 1 and 2, the dielectric sheet 25 is biased against the bottom of the housing 13 by wire contact transfer springs 30. In FIG. 1, the two outer or end springs normally are in contact with supply terminals 40 and 41 and with edge tabs 42 and 43 adherent to the dielectric sheet 25 and connecting with conductors 20 and 21, respectively, as shown in FIG. 5. In this manner, energizing current is supplied to the coils 23 and 24. Of course, it is possible to supply the energizing current in difierent ways, such as in FIG. 6, where a flexible lead 50 is permanently attached to the terminal 41 and to a side tab 51, or as in FIG. 12. In FIG. 12, the terminal 41 is adapted to bear against the side tab 51 as the dielectric sheet 25 is moved. A spring 70 may be utilized to bias the dielectric sheet 25. The transfer contact springs 38 are normally in contact with transfer contacts 44, FIG. 2, and with normally closed contacts 45. When an energizing current is supplied to the coils 23 and 24, the dielectric sheet is forced away from the bottom of the housing 13 carrying the transfer contact springs 30 away from the normally closed contacts 45 and into contact with normally open contacts 46. The dielectric sheet 25 will remain displaced so long as the energizing current is supplied.

It is recognized that other contact arrangements are possible, such as shown in FIG. 4. Contact transfer springs 60 and 61 are associated with terminals 62 and 63, respectively, and with a common terminal 64. The contact 61 is normally in contact with the terminal 64, while the contact 60 is normally held out of contact with the terminal 64 by the dielectric sheet 25, which is slotted to permit the contact 60 to pass therethrough. The contacts 60 and 6-1 are prestressed to be urged into contact with the terminal 64. Hence, the dielectric sheet is biased by springs 71 to hold the contact 60 away from the terminal 64. When an energizing current is supplied to the coils 23 and 24, the dielectric sheet 25 is displaced so as to carry the contact 61 away from the terminal 64 and permit the contact 60 to come against the terminal 64. Of course, the contact 60 aids the dielectric sheet in its displacement. If it is desirable to transfer the contact 61 prior to the transfer of contact 60, the dielectric sheet 25 could be positioned to abut the contact 61 to bias the same so as to hold the contact 60 away from the terminal 64.

In FIG. 11, a hairpin type of transfer contact 75 is connected to a terminal 76 and has one leg 77 normally in contact with a terminal 78 and another leg 79 adapted to make contact with a terminal 80 when permitted to do so by the dielectric sheet 25. The dielectric sheet 25 is provided with an aperture to permit the legs 77 and 79 to pass therethrough. The contact legs 77 and 79 are prestressed to be normally urged into contact with the associated terminals 78 and 80, respectively. The dielectric sheet 25 is biased by springs, not shown, in a manner to permit the contact leg 77 to make contact with the associated terminal 78 and to hold the contact leg 79 out of contact with its associated terminal 80. When an energizing current is supplied to the coils 23 and 24, the dielectric sheet 25 is displaced so as to carry the contact leg 77 away from the terminal 78 and permit the contact leg 79 to make contact with the terminal 80. The contact leg 77 is carried away from the terminal 78 substantially at the same time the contact leg 79 makes contact with the terminal 80. If it is desired to move the contact leg 77 away from the terminal 78 prior to the contact leg 79 making contact with the terminal 80, the lower edge of the aperture in the dielectric sheet 25 is positioned to normally abut the contact leg 77.

In FIG. 8, the dielectric sheet 25 carries a Z-shaped terminal having a central portion 86 in constant sliding contact with a common terminal 87. The central portion 86 is joined to an arm 88 normally in sliding contact with a terminal 89 and to an arm 90 normally out of contact with an associated terminal 91. When an energizing current is supplied to the coils upon the dielectric sheet 25, the same is displaced so that the arm 88 slides out of contact with the terminal 89 and the arm 90 slides into contact with the terminal 91, while the central portion 86 remains in sliding contact with the terminal 87.

Another type of sliding contact arrangement is shown in FIG. 9. The dielectric sheet 25 carries a terminal 92 which is adapted to slide relative to terminals 93 and 94 so as to establish and interrupt an electrical connection therebetween as the dielectric sheet 25 is moved in the manner described above. The dielectric sheet may be biased so that the terminal 92 is normally in or out of contact with the terminals 93 and 94.

In FIG. =10, an edge terminal 95 is adapted to establish and interrupt an electrical connection between terminals 96 and 97 as the dielectric sheet 25 carrying the terminal 95 moves the same into and out of contact with the terminals 96 and 97.

From the foregoing, it is seen that a relay has been provided whereby the member for actuating the contacts is displaced with a uniform force. It is also seen that the relay is of simple construction and lends itself to automated techniques including those for printed circuitry.

While the invention has been particularly shown and described with reference to preferred embodiments there of, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. An electrodynamic relay comprising: a frame member having a central rib; a pair of permanent magnetic members provided with a slot to form the poles thereof mounted relative to said frame member whereby said rib spaces said magnetic members from each other to form a gap therebetween, said magnetic members being disposed whereby opposite poles are opposite each other; a linearly movable dielectric sheet disposed within said gap and resting upon said rib; means for biasing said dielectric sheet against said rib; a pair of series connected fiat coils carried upon opposite sides of said dielectric sheet; at least one pair of electrical contacts, the relative motion of which is controlled by the linear motion of said dielectric sheet; and terminals connected to supply an energizing current to said coils.

2. An electrodynamic relay according to claim 1 Wherein said terminals are adapted to bias said dielectric sheet against said frame.

3. An electrodynamic relay according .to claim 1 wherein the width of said slot in said magnetic members is substantially equal to twice the distance of said gap.

4. An electrodynamic relay according to claim 3 wherein the depth of said slot in said magnetic members is substantially equal to the width of said slot.

5. An electrodynamic relay comprising: a frame member having a central rib; a pair of permanent magnetic members, each provided with a slot to form the poles thereof, mounted relative to said frame member whereby said rib spaces said magnetic members to form a gap therebetween, said magnetic members being disposed so that opposite poles are opposite each other; a linearly movable dielectric sheet disposed within said gap to abut against said central rib, said dielectric sheet having an aperture therein; a pair of electrical contacts, the relative motion which is controlled by the motion of said dielectric sheet, one of said contacts extends through said aperture in said dielectric sheet; and a fiat coil carried by said dielectric sheet so that substantially the entire coil is between said pair of magnetic members and whereby, upon electrical energization of said flat coil, said dielectric sheet is linearly moved to move at least said one contact relative to the other contact.

6. An electrodynamic relay according to claim 5 fur ther comprising: means for biasing said dielectric sheet so that said one contact is held away from the other contact.

7. An electrodynamic relay according to claim 6 further comprising: a contact normally abutting said other contact and adapted to be moved away therefrom by said dielectric sheet.

References Cited in the file of this patent UNITED STATES PATENTS 318,345 Boyle May 19, 1885 1,628,115 Call May 10, 1927 1,628,991 Miller May 17, 1927 1,668,998 Bruce May 8, 1928 2,053,619 Le Goff Sept. 8, 1936 2,666,879 Godsey et al Jan. 19, 1954 2,773,239 Parker Dec. 4, 1956 2,799,746 Raymond July 16, 1957 2,847,619 Shafer Aug. 12, 1958 2,936,353 Hanlet May 10, 1960 2,997,560 Callaway Aug. 22, 1961 

